﻿Shader "Custom/Sprite Scrolling" {
    Properties {
        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
        _Color("Tint", Color) = (1,1,1,1)
        _ScrollSpeed("Scroll Speed", Vector) = (0,0,0,0)
        [MaterialToggle] PixelSnap("Pixel snap", Float) = 0
        [HideInInspector] _RendererColor("RendererColor", Color) = (1,1,1,1)
        [HideInInspector] _Flip("Flip", Vector) = (1,1,1,1)
        [PerRendererData] _AlphaTex("External Alpha", 2D) = "white" {}
        [PerRendererData] _EnableExternalAlpha("Enable External Alpha", Float) = 0
    }
 
    SubShader {
        Tags {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
            "PreviewType" = "Plane"
            "CanUseSpriteAtlas" = "True"
        }
 
        Cull Off
        Lighting Off
        ZWrite Off
        Blend One OneMinusSrcAlpha
 
        Pass {
            CGPROGRAM
            #pragma vertex SpriteVertScrolling
            #pragma fragment SpriteFrag
            #pragma target 2.0
            #pragma multi_compile_instancing
            #pragma multi_compile_local _ PIXELSNAP_ON
            #pragma multi_compile _ ETC1_EXTERNAL_ALPHA
            #include "UnitySprites.cginc"
 
            float2 _ScrollSpeed;
 
            // A copy of SpriteVert() from builtin_shaders-2019.1.7f1/CGIncludes/UnitySprites.cginc
            v2f SpriteVertScrolling(appdata_t IN) {
                v2f OUT;
 
                UNITY_SETUP_INSTANCE_ID(IN);
                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
 
                OUT.vertex = UnityFlipSprite(IN.vertex, _Flip);
                OUT.vertex = UnityObjectToClipPos(OUT.vertex);
                OUT.texcoord = IN.texcoord;
                OUT.texcoord.x += _Time * _ScrollSpeed.x;
                OUT.texcoord.y += _Time * _ScrollSpeed.y;
                OUT.color = IN.color * _Color * _RendererColor;
 
                #ifdef PIXELSNAP_ON
                OUT.vertex = UnityPixelSnap(OUT.vertex);
                #endif
 
                return OUT;
            }
 
            ENDCG
        }
    }
}